// examples/embed.c -- add scripting to a C program with calog, in ~40 lines.
//
// The entire embedding surface is calog.h: create a runtime, register a native C
// function the host provides, open a script context on an engine, fire-and-forget a
// script, and calogPump on the host thread to service the script's calls back into
// the host. Swap calogJsEngine for calogLuaEngine / calogSquirrelEngine to change
// languages -- nothing else changes.

#define _POSIX_C_SOURCE 200809L

#include "calog.h"

#include <stdio.h>
#include <time.h>

// A host-provided native, callable from any embedded engine. Runs on the host thread
// (this one), during calogPump -- so it can touch host state without locking.
static int32_t hostLog(CalogValueT *args, int32_t argCount, CalogValueT *result, void *userData) {
    (void)userData;
    calogValueNil(result);
    if (argCount != 1 || args[0].type != calogStringE) {
        return calogFail(result, calogErrArgE, "hostLog expects one string");
    }
    printf("[host] %s\n", args[0].as.s.bytes);
    return calogOkE;
}


int main(void) {
    CalogT          *calog;
    CalogContextT   *ctx;
    struct timespec  tick = { 0, 1000000 };   // 1 ms
    int              i;

    calog = calogCreate();
    calogRegister(calog, "hostLog", hostLog, NULL);

    ctx = calogContextOpen(calog, &calogJsEngine);
    calogContextEval(ctx, "hostLog('hello from JavaScript, ' + (6 * 7))");

    // A real host pumps calog inside its own main loop; here we tick briefly so the
    // fire-and-forget script gets to run and call hostLog on this thread.
    for (i = 0; i < 50; i++) {
        calogPump(calog);
        nanosleep(&tick, NULL);
    }

    calogContextClose(ctx);
    calogDestroy(calog);
    return 0;
}